ICD-10 T84.023A
Billable / Specific HCC v28: 176 CCInstability of internal left knee prosthesis, initial encounter
About ICD-10-CM T84.023A
ICD-10-CM code T84.023A represents Instability of internal left knee prosthesis, initial encounter. This is a billable/specific code in the Injury, Poisoning, and External Causes chapter (block T84). The 2026 edition of ICD-10-CM T84.023A became effective on October 1, 2025.
Coding Tips for T84.023A
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
T84.023A is a CMS-HCC v28 risk-adjustment code (category 176). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
T84.023A is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Injury codes require a 7th character: A (initial encounter, active treatment), D (subsequent, healing/recovery), S (sequela, late effect of original injury). Codes with fewer than 6 characters need the placeholder X to bring them to 6 characters before adding the 7th. Wrong or missing 7th character is the #1 cause of injury claim denials.
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Inpatient DRG Impact, CC
codes Instability of internal left knee prosthesis, initial encounter. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for T84.023A
Local Coverage Determinations (LCDs) from CMS MACs that list T84.023A as a covered diagnosis.
Showing top 10 of 116 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing T84.023A.
5 Medicare
CPT Codes Commonly Billed with T84.023A
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Convert T84.023A to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| T84.023A | 99642 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
ICD-10 T84.023A, Billing FAQ
Is ICD-10 code T84.023A billable? +
Yes, T84.023A is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Does T84.023A affect Medicare Advantage HCC risk adjustment? +
Yes. T84.023A maps to CMS-HCC v28 category 176. Capture this diagnosis annually for accurate Medicare Advantage risk score.
Is T84.023A a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What ICD-9 codes does T84.023A map to? +
Per CMS GEMs, T84.023A maps to ICD-9 codes: 99642. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on April 23, 2026.
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